We’ve increasingly seen users get more creative with their Twitter marketing campaigns, and the latest is the Twitter NASCAR campaign launched by Brad Keselowski.

Yahoo Sports spotted the campaign that started with a tweet:

So what are Keselowski’s followers winning? The chance to have their Twitter usernames on his car. You have to retweet Keselowski with your prediction, and of course follow him and his race sponsors Reese Towpower and Cooper Standard on Twitter, with just over 2,000 followers each.

That might not seem like much until you realize that Reese Towpower only had 150 followers before the campaign launched less than half a day ago, increasing almost 1,500% in a matter of hours.

5,000 users will be selected randomly to get their usernames into the NASCAR arena, featured on his car’s decklid, while 10 will get the distinction of having their names on the side of his car.

Twitter has already proven to be the ideal tool to make a social media campaign go viral. Encouraging retweets as a way of entering a competition is a surefire way to get the word out about your product or brand, but it also treads a fine line between marketing and spam.

Another issue this kind of campaign highlights is Twitter’s own role in all of this. As The Next Web’s Paul Sawers pointed out, brands are paying celebs to tweet about their products, and the middle man, Twitter, isn’t getting a cut of the money.

A viral marketing campaign like this takes advantage of a free service provided by Twitter, but at least in this case, the social network is getting a little bit of publicity of its own. While the focus is on Keselowski’s fans – it’s not their names that are going to be plastered all over his car – it’s their Twitter usernames.

Of course the usernames will probably be impossible to spot while he’s whizzing around the track, but the campaign shows how Twitter can really find its way into any field or industry – even NASCAR. And how the world of sports advertising is discovering less traditional methods to get the word out.

Wonder what the most successful Twitter brands of 2011 were? Check out some of our favourites here.